Spacer suited for being embedded in concrete

ABSTRACT

Spacer suited for being embedded in concrete, for use with wire reinforcements placed in the walls of concrete pipes cast in molds. One side of a basic body is provided with radially projecting mounting elements for connecting the basic body with the wire reinforcement. The radially opposite other side of the basic body is equipped with a spacer element projecting in radially opposite direction relative to the mounting elements and terminating by an inclined surface which extends substantially in axial direction for assisting the sliding movement when mounting the mold.

The present invention relates to a spacer suited for being embedded inconcrete, for use with wire reinforcements placed in the walls ofconcrete pipes cast in molds, wherein radially projecting mountingelements for connecting the basic body with the wire reinforcement areprovided on one side of a basic body, the radially opposite other sideof the basic body being equipped with a spacer element projecting inradially opposite direction relative to the mounting element andterminating by an inclined surface which extends substantially in axialdirection for assisting the sliding movement when mounting the mold.

A spacer of the type described above has been known from U.S. Pat. No.4,741,143. The spacer disclosed by this publication serves for securinga reinforcing cage inside a cylindrical hole at a certain distance fromthe walls of the hole, which is to be filled completely with castingconcrete, for the production of a solid column.

The side of the spacer where the latter is to be joined with the wirereinforcement displays mounting elements in the form of projecting wireswhich must be wound around the wire reinforcement for establishing theconnection. The wall of the hole which is to be filled with castingconcrete practically constitutes the mold for the solid cylindricalblock to be produced. In order to enable the reinforcing cage, with thespacers fixed thereon, to be introduced in the axial direction and inwell-centered relationship into the cylindrical opening to be filledwith the casting concrete, the side of the spacer opposite the wiremounting elements is equipped with an oblique surface which extends inthe axial direction and which is intended to facilitate the slidingmovement.

However, it is a drawback of the spacer of the type described above thathandling is extremely arduous, i.e. that mounting the spacer on thereinforcement is extremely time-consuming. The reason is that the wireshave to be bent around the reinforcing bars and to be joined with thelatter by twisting. The spacer as such consists of concrete in which themounting elements are embedded. In spite of the oblique sliding surfaceprovided, it cannot be excluded that gripping or jamming may occurbetween the relatively rough concrete material and a rough moldmaterial, which may then lead to parts breaking off the spacer. Inaddition, a spacer of this type is not capable of resisting stresses inthe circumferential direction. In the case of heavy circumferentialstresses it cannot be excluded that the spacer may tilt laterally sothat it can no longer guarantee the correct spacing in the radialdirection, even if it may perhaps be caught by the reinforcement.

However, the described kind of stress, i.e. a force component acting inthe circumferential direction, in fact is encountered in the productionof cast concrete pipes. The mold used for such concrete pipes consistsof an outer cylindrical mold and an inner central core which twoelements define between them an annular space which is then filled withconcrete. In contrast to the process of casting solid columns, where theconcrete can be introduced centrally and where the poured concrete risesslowly, thus producing predominantly radial flow phenomena, pouringconcrete into an annular cylindrical space gives rise also to acircumferential flow component. This is so because when concrete ispoured at one point into the hollow mold of a concrete pipe, theconcrete spreads uniformly in a substantially circumferential direction.The required spreading motion and compacting of the concrete is assistedby the use of vibrators, with the result that the wire reinforcement islikewise set into vibrating movement. This gives rise to forces actingin the circumferential direction which tend to displace the reinforcingcage in the circumferential direction, relative to the mold. In thepresence of such stresses, a spacer of the type described above wouldtilt laterally so that there would be a risk of the reinforcement beingembedded in the pipe in non-coaxial alignment.

DE-U 8704 698 describes a spacer for heavy reinforcements which consistsof a concrete polymer and in which mounting elements are embedded in theform of wire loops. Although a spacer of this type is capable ofabsorbing considerable pressure in a direction vertical to the surfaceof the wire reinforcing mats, laterally directed forces may lead to thespacer coming off the reinforcement.

Now, it is the object of the present invention to provide a spacer whichis easy to produce, easy to handle, which enables the wire reinforcementto slide smoothly in the axial direction relative to the mold, and whichis suited to absorb not only radial forces, but also circumferentialforces in such a way that a firm connection between the spacer and thereinforcement is guaranteed.

The invention achieves this object by the fact that the mountingelements are designed as resilient elements and can be clicked upon thewire reinforcement, that the basic body consists of a concrete polymerwith at least two mounting elements, which enclose the wirereinforcement at least partially in form-locking engagement, beingembedded in thicker material portions of the basic body, at a certaindistance one from the other, viewed in the circumferential direction ofthe concrete pipe to be poured.

The resilient design of the mounting elements enables the spacer to beclicked easily upon the wire reinforcement. The fact that the mountingelements enclose the wire reinforcement partially in form-lockingengagement ensures a firm, undetachable connection. As two mountingelements are provided at a certain distance one from the other, viewedin the circumferential direction, the spacer not only rests against thereinforcement at the point of contact of the basic body, but isadditionally connected to it at the same level via two additional pointsspaced therefrom. To say it in other words, the spacer is in contactwith the wire reinforcement in the circumferential direction over aconsiderable length. The mounting elements which are clicked upon thereinforcing bars and which enclose the latter partially in form-lockingengagement guarantee the firm seat of the spacer on the reinforcement.The large contact surface, in the circumferential direction, ensuresthat the spacer cannot tilt under the action of forces acting in thecircumferential direction. This behavior is further supported by thefact that the mounting elements are cast into thicker portions of theconcrete which excludes the risk of the mounting elements being torn outof the spacer under the action of high circumferential stresses.However, the known measure of making the spacers from a concrete polymerprovides the additional advantage that the spacers are easy to produceand that the spacers can be given a smooth, easily sliding and closedsurface which permits a relative movement in axial direction between thespacers, after they have been clicked upon the reinforcement, and thewall of the mold, without any risk of jamming or breakage of the spacermaterial, as would be the case with spacers made from usual concrete.

The object underlying the invention is, thus, achieved in full.

According to a further improvement of the invention, the mountingelements are designed as wire elements projecting from the basic body.

This feature provides the advantage that, depending on the size of theconcrete pipe to be produced, very strong and high-quality wire elementscan be cast into the concrete so that even extremely highcircumferential forces can be absorbed by these wire elements, i.e. thaton the one hand they cannot be bent open in the area where they enclosethe reinforcing bar partially in form-locking engagement and that on theother hand they are firmly seated in the concrete polymer in which theyare embedded.

Another embodiment of the invention provides that some of the mountingelements engage peripheral sections, and other mounting elements engageaxial sections of the wire reinforcement.

This feature, which is known per se, ensures in conjunction with thecombined features of the invention an undetachable seat for the spacer,once it has been clicked upon the reinforcement, and guarantees that allforces acting in the radial, axial and even in oblique or diagonaldirection, can be absorbed without the spacer getting detached. Obliqueforces may occur, for example, when the reinforcing cage comes to rotatewhen it is lowered axially into the mold. The design of the spacersproposed by the invention then excludes the risk that some of thespacers may be torn off already at the time of insertion of the cage, ifthe latter should rotate.

According to another embodiment of the invention, the side of the basicbody which carries the mounting elements is provided with at least onegroove for receiving a section of the wire reinforcement.

It is particularly advantageous in this connection to provide at leastone groove for receiving an axial section.

This feature provides the advantage that the spacer comes to rest on thecorresponding reinforcing bar in form-locking engagement, in the area ofthe groove. In combination with the mounting elements arranged on bothsides of the axial reinforcing bar engaged in the groove, this thenprovides an intimate connection between the spacer and thereinforcement, which on the one hand can be established by a simpleclick-on or snap-on operation and which on the other hand resists evenextremely important stresses in the circumferential direction. Ofcourse, this connection is also capable of resisting important axialstresses in the snap-on direction.

According to another embodiment of the invention, the spacer element hasthe shape of a segment of a circle, the center of the circle coincidingsubstantially with a mounting element which engages a peripheral sectionof the wire reinforcement. The vertex of the circle defines the pointwhich is the most remote from the point at which the spacer is fixed onthe reinforcing cage. It is the point where the spacer is in contactwith the mold. Now, the greatest possible force or tilting momentoccurs, due to the leverage phenomenon, when a relative movement occursin the circumferential direction between the spacer and the mold, whichis in contact with the latter at the vertex of the curvature. Thistilting moment is counteracted in the best possible way by theadvantageous arrangement of the mounting element at the level of thecenter.

Further details of the invention will become apparent from the followingdescription of preferred embodiments of the invention in conjunctionwith the attached drawing, in which:

FIG. 1 is a diagrammatic view of a mold intended for casting concretepipes, with two wire reinforcements arranged in the concrete wall;

FIG. 2 shows a cross-sectional view along line 2--2 in FIG. 1;

FIG. 3 shows a cross-sectional view of the detail indicated by thecircle A in FIG. 1;

FIG. 4 shows a perspective view of a first spacer; and

FIG. 5 shows a perspective view of a second spacer.

The mold illustrated in FIG. 1, which is intended for casting concretepipes of relatively large dimensions, for example in lengths of 3 m andwith diameters of 1.20 m, comprises an inner core 1 projecting upwardlyfrom a circular base plate over a length corresponding to the length ofthe concrete pipe to be cast. The inner core 1 is enclosed by an innerwire reinforcement 3 and an outer wire reinforcement 4 spaced a certaindistance from the said wire reinforcement 3. The wire reinforcements 3,4 comprise vertically extending metal bars 5 which also correspondsubstantially to the length of the finished concrete pipe and which aresupported by the base plate 2. The metal bars 5 are connected, forexample by welding, to substantially circular peripheral sections 6which likewise consist of metal. Usually, the sections 6 form a spiralalong the vertical bars 5. Consequently, the inner and outer wirereinforcements 3, 4 form self-supporting cages which may also beconnected to each other.

Spacers 7, 8--which will be described in more detail furtherbelow--mounted on the wire reinforcements 3, 4 serve to hold the latterin a concentric position relative to the center axis of the inner core1, and at an exactly defined spacing therefrom, the inner spacer 7,which is connected to the inner wire reinforcement, being in contactwith the outer circumferential surface of the inner core 1, while thespacers 8, which are connected with the outer wire reinforcement, are incontact with an outer mold 9 which is fitted upon the inner core 1, inthe direction indicated by arrow B, after the wire reinforcements 3, 4with the spacers 7, 8 mounted thereon have been arranged about the innercore 7.

As the inner wire reinforcement 3 is mounted on the inner core 1, thespacers 7 slide along the latter's outer circumferential surface andensure in this manner that the inner reinforcement is exactly centered.When the inner wall of the outer mold 9 is mounted on the inner core 1,it slides along the spacers 8 whereby the wire reinforcement 4 iscentered.

Once the wire reinforcements 3, 4 have been mounted on the inner coreand the outer mold 9 has been fitted in place, concrete is filled intothe space between the inner core 1 and the mold 9, in the area of thewire reinforcements 3, 4. The inner core 1, together with the base plate2 supporting the outer mold 9, are preferably placed on a vibratingtable so that the concrete, which has been filled into the mold, can becompacted as desired.

FIGS. 3 to 5 illustrate in detail the structure and operation of thespacers 7, 8.

The spacer 7 mounted on the inner wire reinforcement 3 comprises a basicbody 11 made from a material whose thermal coefficient of expansion issubstantially equal to that of the concrete used for the production ofthe pipe. Preferably, a concrete polymer, i.e. a mixture of a plasticmaterial and sand, cement or the like, may be used for this purpose. Oneside of the basic body 11 (the right side in FIGS. 3 and 4) is providedwith radially projecting mounting elements which serve as connectionbetween the basic body and the inner wire reinforcement 3. Thesemounting elements comprise two lower wire elements 12 of curved shapewhich project from the basic body 11 and which are firmly inserted intothe latter. Each of these wire elements 12 is intended for receiving aperipheral portion 6 of the wire reinforcement 3 from below, inform-locking or frictional engagement, and can be clicked easily uponthe matching section 6. Two further wire elements 13 arranged one besidethe other above the wire elements 12 engage the metal bar in frictionalor form-locking manner so that they, too, enable the mounting element tobe clicked upon the bar 5.

The side of the basic body 11 radially opposite the wire elements 12, 13is equipped with a spacer element 14 in the form of a rib which projectsin a direction radially opposite to the wire elements 12, 13 and whichterminates by an inclined surface 15 extending substantially in axialdirection and serving to facilitate the sliding movement along the innercore 1.

As appears from FIGS. 1 and 2, several spacers 17 are mounted invertically and peripherally spaced arrangement on the inner wirereinforcement before the latter is positioned on the inner core 1.During the sliding positioning movement, the inclined surfaces 5 slidealong the outer surface of the inner core 1 so that the highest point ofthe rib 14 projecting the farthest to the inside comes to rest againstthe inner core 1 whereby it ensures the desired centering of the wirereinforcement 3. As the wire elements 12 embrace the sections 6 of thereinforcement from below, the spacers 7 are prevented from beingdislodged in upward direction by the sliding movement between thereinforcement 3 and the inner core 1.

Advantageously, an additional section 6 of the reinforcement is leftbetween the two wire elements 12, 13 for supporting the wall of thebasic body from which the wire elements 12, 13 project (see FIG. 3).

The spacer 8 provided on the outer wire reinforcement 4 compriseslikewise a basic body 16 consisting, for example, of a concrete polymer.Two wire elements 17 projecting from the upper end of the said body 16correspond substantially to the wire elements 11 provided on the spacer7, except that they engage the matching peripheral section 6 of the wirereinforcement from above, rather than from below. The wall from whichthe wire elements 17 project is provided with a groove 18 receiving partof the vertically extending metal bar thereby providing a verticalsupport for the spacer 8. The basic body 16 is again provided, on theside opposite the wire element 17, with a rib 19 with an inclinedsurface 21. When the outer wire reinforcement 4, together with thespacers 8, is placed upon the base plate 2 of the inner mold core 1 andthe outer mold 9 is moved in place over the assembly, the outer moldcomes to slide initially along the inclined surfaces 21 of the spacers8, thereby centering the reinforcement 4, while in the end position thecrown points of the rib 19 projecting the farthest in the radialdirection come to rest against the inner face of the outer mold 9.

As illustrated in the drawing, all of the peripheral sections 6 of thewire reinforcements 3, 4 are arranged on the sides of the vertical metalbars 6 facing the inner core 1. It is ensured in this manner that thewall from which the wire elements 12, 13 of the spacer 7 project restsagainst peripheral sections 6 of the wire reinforcement 3, while thegroove 18 of each spacer 8 engages a vertical bar 5.

The design of the spacers 7, 8 and their connection with the wirereinforcements 3, 4 are sturdy enough to ensure that they cannot getdislodged or distorted by any relative movements between thereinforcements and the parts 1 and 9 of the mold so that thereinforcements 3, 4 will in any case occupy an exactly centered positionin the annular space of the mold to be filled with concrete. Thedistance between the wire reinforcements 3, 4 and the inner core 1 ofthe outer mold 9 is determined in any case by the crown heights of theprojecting ribs 14, 19.

In the case of the embodiments of the mounting elements, i.e. the wireelements 12, 13 and 17, described so far all these elements are designedas parts separate from the basic body 11, 16. However, according tocertain modified embodiments of these spacers, the mounting elementswhich serve for connecting the spacers with the wire reinforcements 3, 4may also be formed integrally with the basic body 11, 16 which meansthat they may also consist of a concrete polymer, for example, and maybe formed together with the spacers 7, 8 by the same molding orinjection-molding process. For example, the basic bodies 11, 16 may beprovided with projections which may be formed integrally from a concretepolymer and which may have a height similar to that of the wire elements12, 13, 17, for engaging the wire reinforcements 3, 4 in the same manneras the wire elements 12, 13 and 17.

As appears particularly clearly from FIG. 3, the crown of the curved rib14, which performs the funcion of a spacer element, has the shape of asegment of a circle whose center coincides substantially with the centerline of the peripheral section 6 of the wire reinforcement 3 which isengaged by the wire element 12. If, therefore, the spacer 7 should cometo tilt about the peripheral reinforcement section 6, during applicationof the inner reinforcement 3 on the inner core 1, for example due to thefact that the wire elements 13 get dislodged from the metal bar 5, suchtilting would not change in any way the prescribed spacing between thewire reinforcement 3 and the outer wall of the inner core 1 as the crownof the rib 14 would insofar act as a circular roller.

Besides, a similar design in the form a circular disk may be providedalso for the rib 19 in the area of its surface of contact with the innerwall of the outer mold 9. The concrete pipe described with reference toFIGS. 1 and 2 is a pipe with continuous wall. However, the describedspacers can be used similarly for conventional concrete pipes of thetype provided with a slot extending parallel to the pipe axis. Such"slotted" pipes are used, for example, as water drain pipes alonghighways in which case the water running off the road surface enters theinterior of the pipe through the slot.

As will be seen best is FIGS. 3 to 5, the mounting elements (wireelements 12) are arranged in the lower area of the spacer 7, while themounting elements (wire elements 17) are arranged in the upper area ofthe spacer 8.

I claim:
 1. A spacer for being embedded in concrete and adapted forattachment to wire reinforcements placed in the walls of concrete pipescast in molds, wherein the wire reinforcements includes axially orientedwire and circumferentially oriented wire, the spacer comprising:a mainbody made of a polymer concrete,said main body having integrally formedon a first side thereof a spacer element projecting in a first radialdirection and terminating by an inclined surface extending in an axialdirection, and having provided on a second side opposite said first sideat least one groove for receiving a wire of said wire reinforcement; andat least two resilient wire mounting elements extending in a secondradial direction from said second side of main body, said resilientmounting elements having one end embedded in said main body and whereinthe other end of each of said resilient mounting elements is designed tobe clipped on another wire of said wire reinforcement.
 2. Spaceraccording to claim 1, wherein said at least two mounting elementsembedded in said main body are disposed on opposite sides of saidgroove.
 3. Spacer according to claim 1, wherein said spacer element hasthe shape of a segment of a circle, a center of said circle coincidingsubstantially with one of said pairs of mounting elements.
 4. Spacersuited for being embedded in concrete, for use with wire reinforcementsplaced in the walls of concrete pipes cast in molds wherein the wirereinforcements include axially oriented wire and circumferentiallyoriented wire, the spacer comprising:a main body made of a polymerconcrete,said main body is provided at a first side with a spacerelement projecting from said main body in a first radial direction andterminated by an inclined surface extending in an axial direction, saidmain body is provided on a second side with at least one groove forreceiving a wire of said wire reinforcement, said second side beingradially opposite to said first side, said main body is further providedwith at least two mounting elements designed as resilient elementshaving one end embedded in enlarged portions of said main body, saidenlarged portions are disposed on opposite sides of said groove, andwherein said resilient elements project from said second side of saidmain body in a second radial direction, and each resilient element isdesigned to be clipped on another wire of said wire reinforcement. 5.Spacer according to claim 4, wherein said mounting elements are designedas wire elements.
 6. Spacer according to claim 4, wherein said spacerelement has the shape of a segment of a circle, a center of said circlecoinciding substantialy with one of said mounting elements.